Forty-one Boston children hospitalized with non-organic failure-to-thrive (FTT) were matched with 41 control subjects on age, socioeconomic status (SES), sex, and race. A precoded maternal interview was used to evaluate family stress, isolation, infant health, and the temperament and social maturity of the child. A regression analysis was performed with 27 variables thought to be potentially associated with the FTT diagnosis. Ten variables explained 81% of the between group variance onF-tests. The most significant distinctions were poor child health (p< 0.001), high reactivity to visual and auditory stimuli (p< 0.001), and disordered feeding interaction (p< 0.005). Other case-comparison differences included social isolation, few maternal opportunities to escape caregiving, the presence of a male adult in the family, fewer available extended family, fewer violent disagreements between parents, greater number of maternal unmarried years. Children with FTT appeared to have developmental idiosyncrasies. These conspire with social and familial factors to yield the current profile of non-organic FTT. This study questions whether such findings are the cause of FTT or are better understood as a result.J Dev Behav Pediatr 8:32–36, 1987.Index terms:failure-to-thrive, abuse, neglect, development.